Semiconductor integrated circuit device

ABSTRACT

Diffusion regions having the same conductivity type are arranged on a side of a second wiring and a side of a third wiring, respectively under a first wiring connected to a signal terminal. Diffusion regions are separated in a whole part or one part of a range in a Y direction. That is, under first wiring, diffusion regions are only formed in parts opposed to diffusion regions formed under the second wiring and third wiring connected to a power supply terminal or a ground terminal, and a diffusion region is not formed in a central part in an X direction. Therefore, terminal capacity of the signal terminal can be reduced without causing ESD resistance to be reduced, in an ESD protection circuit with the signal terminal.

This application is a continuation application of U.S. application Ser.No. 15/174,236 filed on Jun. 6, 2016, which is a continuation of U.S.application Ser. No. 14/945,378 filed on Nov. 18, 2015 now U.S. Pat. No.9,385,113, which is a continuation of U.S. application Ser. No.14/628,175 filed on Feb. 20, 2015 now U.S. Pat. No. 9,224,725, which isa continuation of U.S. application Ser. No. 14/205,022 filed on Mar. 11,2014, now U.S. Pat. No. 8,994,111, which is a continuation ofInternational Application No. PCT/JP2012/005583, with an internationalfiling date of Sep. 4, 2012, which claims priority of Japanese PatentApplication No. 2011-202824, filed on Sep. 16, 2011, the contents ofeach of which are hereby incorporated by reference.

BACKGROUND

1. Technical Field

The present disclosure relates to a semiconductor integrated circuitdevice and more particularly, to a layout configuration of an ESD(Electro Static Discharge) protection circuit (electrostatic dischargeprotection circuit) for protecting a circuit from being damaged due toelectrostatic discharge.

2. Description of the Related Art

As shown in FIG. 15, in general, ESD protection circuits 51 and 52 areprovided between signal terminal (input/output terminal) 53 and powersupply terminal 54, and between signal terminal 53 and ground terminal55, respectively. As the ESD protection circuit, various protectionelements are used depending on purposes. Representative ones include adiode, a bipolar transistor, a MOS transistor, a thyristor, and thelike.

FIG. 16 shows one example of a layout configuration of a conventionalESD protection circuit. Referring to FIG. 16, diode D serving as theprotection element includes diffusion layers 65 as anodes, and diffusionlayers 64 as cathodes arranged between them. Each of diffusion layers 64and 65 is electrically connected to a wiring connected to aninput/output terminal or the like, through contact holes 63 (UnexaminedJapanese Patent Publication No. 2007-299790, FIG. 16).

SUMMARY

In the case where the above-described ESD protection circuit isprovided, capacity between wirings due to the wiring arrangement, anddiffusion capacity due to junction of the diffusion layers exist betweenthe signal terminal, and the power supply terminal and the groundterminal. Therefore, as for the signal terminal for inputting/outputtinga high-speed signal, its terminal capacity including the capacitybetween the wirings and the diffusion capacity could cause a signalwaveform to deteriorate. Therefore, it is preferable to provide an ESDprotection circuit in which the terminal capacity is reduced, in asemiconductor integrated circuit which inputs and outputs the high-speedsignal especially.

As a method for reducing the terminal capacity, it is considered that asize of the protection element is reduced to reduce the diffusioncapacity. However, in the case where the size of the protection elementis simply reduced, the problem that ESD resistance is reduced occurs. Inaddition, when a wiring width connected to the diffusion layer isreduced, or the number of contacts and the number of via holes arereduced because an area of the diffusion region is reduced, the wiringor the like could be fused by a surge current.

In view of the above problems, it is an object of the present disclosureto reduce terminal capacity of a signal terminal in an ESD protectioncircuit with the signal terminal without causing ESD resistance to bereduced.

According to one aspect of the present disclosure, an ESD protectioncircuit in a semiconductor integrated circuit device includes a firstwiring extending in a first direction and electrically connected to afirst terminal, a second and a third wirings extending in the firstdirection, electrically connected to a power supply terminal or a groundterminal, and arranged on both sides of the first wiring, respectively,a first and a second diffusion regions formed under the first wiring,having a same first conductivity type, arranged on a side of the secondwiring and a side of the third wiring, respectively in a seconddirection perpendicular to the first direction, and separated in a wholepart or one part of a range in the first direction, a third diffusionregion formed under the second wiring, having a second conductivitytype, and arranged so as to be opposed to the first diffusion region inthe second direction, and a fourth diffusion region formed under thethird wiring, having the second conductivity type, and arranged so as tobe opposed to the second diffusion region in the second direction. Underthe first wiring connected to the first terminal, the first and seconddiffusion regions having the same conductivity type are arranged on thesides of the second wiring and the third wiring, respectively, and thefirst and second diffusion regions are separated in the whole or onepart in the area of the wiring extending in the first direction. Thatis, under the first wiring, the diffusion region is formed only theparts opposed to the third and fourth diffusion regions formed under thesecond and third wirings connected to the power supply terminal or theground terminal, and the diffusion region is not formed in the centralpart in the second direction perpendicular to the first direction.Therefore, an area of the diffusion region in the protection element canbe reduced, so that terminal capacity of the first terminal can bereduced. In addition, in the area opposed to the diffusion region on theside of the power supply terminal or the ground terminal, the diffusionregion is not reduced, so that the discharge ability of the protectionelement is not reduced. Furthermore, a wiring width of the first wiring,and the number of contacts and the number of via holes are sufficientlyensured, so that reduction in discharge ability due to the fusion is notgenerated.

According to another aspect of the present disclosure, an ESD protectioncircuit in a semiconductor integrated circuit device includes a firstwiring extending in a first direction and electrically connected to afirst terminal, a second and a third wirings extending in the firstdirection, electrically connected to a power supply terminal or a groundterminal, and arranged on both sides of the first wiring, respectively,a first diffusion region formed under the first wiring, and having afirst conductivity type, and a second diffusion region formed under thesecond wiring, having a second conductivity type, and arranged so as tobe opposed to the first diffusion region in a second directionperpendicular to the first direction, a third diffusion region formedunder the third wiring, having the second conductivity type, andarranged so as to be opposed to the first diffusion region in the seconddirection, in which in a range including the first diffusion region andthe second diffusion region opposed to each other, an interval betweenthe first wiring and the second wiring is larger than an intervalbetween the first diffusion region and the second diffusion region, andin a range including the first diffusion region and the third diffusionregion opposed to each other, an interval between the first wiring andthe third wiring is larger than an interval between the first diffusionregion and the third diffusion region. The first diffusion region formedunder the first wiring connected to the first terminal is opposed to thesecond and third diffusion regions formed under the second and thirdwirings connected to the power supply terminal or the ground terminal,respectively. Thus, in the range including the diffusion regions opposedto each other, the interval between the wirings is larger than theinterval between the diffusion regions. Therefore, capacity betweenwirings can be reduced, so that terminal capacity of the first terminalcan be reduced.

According to the present disclosure, the terminal capacity of the signalterminal can be reduced without impairing the ability as the protectionelement.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a view showing a layout configuration regarding an ESDprotection circuit of a semiconductor integrated circuit deviceaccording to a first exemplary embodiment;

FIG. 1B is a view showing the layout configuration regarding the ESDprotection circuit of the semiconductor integrated circuit deviceaccording to the first exemplary embodiment;

FIG. 2A is a view showing a layout configuration according to avariation of the first exemplary embodiment;

FIG. 2B is a view showing the layout configuration according to thevariation of the first exemplary embodiment;

FIG. 3A is a view showing a layout configuration according to avariation of the first exemplary embodiment;

FIG. 3B is a view showing the layout configuration according to thevariation of the first exemplary embodiment;

FIG. 4A is a view showing a layout configuration in a case where the ESDprotection circuit is a thyristor type in FIG. 1;

FIG. 4B is a view showing the layout configuration in the case where theESD protection circuit is a thyristor type in FIG. 1;

FIG. 5A is a view showing another example of the layout configurationaccording to the first exemplary embodiment;

FIG. 5B is a view showing the other example of the layout configurationaccording to the first exemplary embodiment;

FIG. 6A is a view showing another example of the layout configurationaccording to the first exemplary embodiment;

FIG. 6B is a view showing the other example of the layout configurationaccording to the first exemplary embodiment;

FIG. 7A is a view showing another example of the layout configurationaccording to the first exemplary embodiment;

FIG. 7B is a view showing the other example of the layout configurationaccording to the first exemplary embodiment;

FIG. 8A is a view showing a layout configuration regarding an ESDprotection circuit of a semiconductor integrated circuit deviceaccording to a second exemplary embodiment;

FIG. 8B is a view showing the layout configuration regarding the ESDprotection circuit of the semiconductor integrated circuit deviceaccording to the second exemplary embodiment;

FIG. 9A is a view showing a layout configuration according to avariation of the second exemplary embodiment;

FIG. 9B is a view showing the layout configuration according to thevariation of the second exemplary embodiment;

FIG. 10A is a view showing a layout configuration in a case where theESD protection circuit is a thyristor type in FIG. 8;

FIG. 10B is a view showing the layout configuration in the case wherethe ESD protection circuit is the thyristor type in FIG. 8;

FIG. 11A is a view showing another example of the layout configurationaccording to the second exemplary embodiment;

FIG. 11B is a view showing the other example of the layout configurationaccording to the second exemplary embodiment;

FIG. 12A is a view showing a layout configuration regarding an ESDprotection circuit of a semiconductor integrated circuit deviceaccording to a third exemplary embodiment;

FIG. 12B is a view showing the layout configuration regarding the ESDprotection circuit of the semiconductor integrated circuit deviceaccording to the third exemplary embodiment;

FIG. 13A is a view showing another example of the layout configurationaccording to the third exemplary embodiment;

FIG. 13B is a view showing the other example of the layout configurationaccording to the third exemplary embodiment;

FIG. 14A is a view showing another example of the layout configurationaccording to the third exemplary embodiment;

FIG. 14B is a view showing the other example of the layout configurationaccording to the third exemplary embodiment;

FIG. 15 is a circuit diagram showing a relationship between a signalterminal and the ESD protection circuit; and

FIG. 16 is a view showing an example of a layout configuration regardinga conventional ESD protection circuit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, exemplary embodiments of the present disclosure will bedescribed with reference to drawings.

First Exemplary Embodiment

FIGS. 1A and 1B are views showing a layout configuration regarding anESD protection circuit of a semiconductor integrated circuit deviceaccording to a first exemplary embodiment. FIG. 1A is a plan view takenfrom above a substrate, and FIG. 1B is a cross-sectional view takenalong a line A-B in FIG. 1A.

First wiring 11 extends in a Y direction (first direction) in FIG. 1A,and electrically connected to a signal terminal (first terminal) whichis not shown. Second wiring 12 and third wiring 13 extend in the Ydirection similarly to first wiring 11, and arranged on both sides offirst wiring 11, respectively. Each of second wiring 12 and third wiring13 is electrically connected to a power supply terminal or a groundterminal which is not shown.

Under first wiring 11, diffusion region 1A serving as a first diffusionregion and diffusion region 1B serving as a second diffusion region areformed. Diffusion region 1A and diffusion region 1B are separatelyarranged on a side of second wiring 12 and a side of third wiring 13, inan X direction (second direction) in FIG. 1A. In other words, firstwiring 11 extends so as to cover diffusion regions 1A and 1B. Diffusionregions 1A and 1B have the same conductivity type.

Under second wiring 12, diffusion region 2 is formed as a thirddiffusion region. Diffusion region 2 is arranged so as to be opposed todiffusion region 1A in the X direction. In addition, under third wiring13, diffusion region 3 is formed as a fourth diffusion region. Diffusionregion 3 is arranged so as to be opposed to diffusion region 1B in the Xdirection. Diffusion regions 2 and 3 have the same conductivity type.

First wiring 11, and diffusion regions 1A and 1B are electricallyconnected through contacts 25. Similarly, second wiring 12 and diffusionregion 2 are electrically connected through contacts 25, and thirdwiring 13 and diffusion region 3 are electrically connected throughcontacts 25. In addition, in FIG. 1A and other plan views, the diffusionregion provided under the wiring is shown so as to be seen through toeasily understand the configuration.

Here, it is assumed that each of second and third wirings 12 and 13 iselectrically connected to the power supply terminal. It is assumed thatthe ESD protection circuit is a diode type in which the signal terminal(first wiring 11) serves as an anode, and the power supply terminal(second and third wirings 12 and 13) serves as a cathode. In this case,diffusion regions 1A and 1B are a P type, and diffusion regions 2 and 3are an N type.

According to the configuration in FIG. 1A, diffusion regions 1A and 1Bare provided under first wiring 11 on an anode side in such a mannerthat parts opposed to diffusion regions 2 and 3 on a cathode side areonly left, and a central part in the X direction is eliminated. As forthe eliminated central part, a transverse distance in a well (N well) islong and resistance is high at the time of discharging as shown bydotted lines in FIG. 1B, so that discharge ability is low, and afunction as the protection element is not sufficiently fulfilled.Meanwhile, as for the part opposed to the cathode, a transverse distancein the well is short and resistance is low at the time of discharging.Therefore, according to this exemplary embodiment, as for the diffusionregion under the first wiring 11 on the anode side, the part opposed tothe cathode side is only left, and the central part is eliminated. As aresult, diffusion capacity can be reduced without impairing the functionas the protection element. Therefore, terminal capacity of the signalterminal can be reduced. In addition, by ensuring a wiring width, thenumber of contacts, and the number of via holes to the extent that asurge current can flow, ESD resistance can be prevented from beingreduced.

In addition, according to the configuration in FIG. 1A, each ofdiffusion regions 1A, 1B, 2, and 3 has a vertically long shape, that is,a rectangular shape in which a dimension in the Y direction along whichthe wiring extends is larger than a dimension in the X direction. Inaddition, diffusion regions 1A and 1B are smaller in width thandiffusion regions 2 and 3, that is, diffusion regions 1A and 1B aresmaller in dimension in the X direction than diffusion regions 2 and 3.However, this exemplary embodiment is not limited to this shape.

FIGS. 2A and 2B are views showing a first variation of this exemplaryembodiment. FIG. 2A is a plan view taken from above a substrate, andFIG. 2B is a cross-sectional view taken along a line A-B in FIG. 2A. InFIGS. 2A and 2B, a component common to that in FIG. 1 is marked with thesame reference sign.

A configuration of FIG. 2 is almost the same as that in FIG. 1. However,there is a difference between them in that an interval between wiringsis larger than an interval between diffusion regions, in a rangeincluding the diffusion regions opposed to each other. Therefore,compared with the configuration in FIG. 1, capacity between wirings isalso reduced, and terminal capacity can be further reduced.

More specifically, in the area including diffusion region 1A anddiffusion region 2 opposed to each other, interval a1 between firstwiring 11 and second wiring 12 is larger than interval b1 betweendiffusion region 1A and diffusion region 2. According to a layout inFIG. 2, diffusion region 1A protrudes toward a side of diffusion region2 from first wiring 11, and diffusion region 2 protrudes toward a sideof diffusion region 1A from second wiring 12, in planar view. Similarly,in the area including diffusion region 1B and diffusion region 3 opposedto each other, interval a2 between first wiring 11 and third wiring 13is larger than interval b2 between diffusion region 1B and diffusionregion 3. According to the layout in FIG. 2, diffusion region 1Bprotrudes toward a side of diffusion region 3 from first wiring 11, anddiffusion region 3 protrudes toward a side of diffusion region 1B fromthird wiring 13, in planar view.

According to this configuration, the interval between first wiring 11and second wiring 12, and the interval between first wiring 11 and thirdwiring 13 are large, so that the capacity between the wirings isreduced, and the terminal capacity can be further reduced.

FIGS. 3A and 3B are views showing a second variation in this exemplaryembodiment. FIG. 3A is a plan view taken from above a substrate, andFIG. 3B is a cross-sectional view taken along a line A-B in FIG. 3A. InFIG. 3, a component common to that in FIG. 1 is marked with the samereference sign.

A configuration in FIG. 3 is almost the same as that in FIG. 1. However,there is a difference between them in that as for the diffusion regionsformed under second wiring 12 and third wiring 13, parts other thanparts opposed to the other diffusion regions are eliminated. Morespecifically, diffusion regions 2A and 2B are formed under second wiring12 so as to be arranged separately on both sides in the X direction, anddiffusion regions 3A and 3B are formed under third wiring 13 so as to bearranged separately on both sides in the X direction. Thus, terminalcapacity of a power supply terminal or a ground terminal can be reduced.

In addition, the configuration of this exemplary embodiment is notlimited to the diode type ESD protection circuit in which the protectionelement serves as the diode, and it can be similarly applied to a casewhere the protection element serves as a bipolar transistor or athyristor. More specifically, the ESD protection circuit according tothis exemplary embodiment may be a bipolar transistor type in which thesignal terminal (first wiring 11) serves as a collector, and the powersupply terminal (second and third wirings 12 and 13) serves as anemitter. In this case, diffusion regions 1A and 1B are the P type, anddiffusion regions 2 and 3 are also the P type. In addition, the ESDprotection circuit according to this exemplary embodiment may be athyristor type in which the signal terminal (first wiring 11) serves asthe cathode, and the power supply terminal (second and third wiring 12and 13) serves as the anode. In this case, as shown in FIG. 4, P-typewell 26 is formed, diffusion regions 1A and 1B are the N type, anddiffusion regions 2 and 3 are the P type.

In addition, second and third wirings 12 and 13 may be electricallyconnected to the ground terminal. In this case, the ESD protectioncircuit according to this exemplary embodiment is a diode type in whichthe ground terminal (second and third wirings 12 and 13) serves as theanode, and the signal terminal (first wiring 11) serves as the cathode.In this case, diffusion regions 1A and 1B are the N type, and diffusionregions 2 and 3 are the P type. In addition, the ESD protection circuitaccording to this exemplary embodiment may be a bipolar transistor typein which the ground terminal (second and third wirings 12 and 13) servesas the emitter, and the signal terminal (first wiring 11) serves as thecollector. In this case, diffusion regions 1A and 1B are the N type, anddiffusion regions 2 and 3 are also the N type. In addition, the ESDprotection circuit according to this exemplary embodiment may be athyristor type in which the ground terminal (second and third wirings 12and 13) serves as the cathode, and the signal terminal (first wiring 11)serves as the anode. In this case, as shown in FIG. 4, N-type well 26 isformed, diffusion regions 1A and 1B are the P type, and diffusionregions 2 and 3 are the N type.

In addition, as shown in FIGS. 5 to 7, the number of parts in which thediffusion region is divided may be further increased. Configurations inFIGS. 5 to 7 correspond to the configurations in FIGS. 1 to 3,respectively. Wiring 14 is electrically connected to a signal terminal,and wiring 15 is electrically connected to a power supply terminal orthe ground terminal. Diffusion regions 4A and 4B are formed under wiring14 so as to be arranged separately in an X direction. In addition, inFIGS. 5 and 6, diffusion region 5 is arranged under wiring 15, and inFIG. 7, diffusion regions 5A and 5B are formed under wiring 15 so as tobe arranged separately in the X direction.

In addition, according to the above-described layout configuration,diffusion regions 1A and 1B are separated in a whole range in the Ydirection, but the configuration is not limited to this, and forexample, a layout configuration may be such that diffusion regions 1Aand 1B are partially connected and one part of them is separated. Inthis configuration also, diffusion capacity can be reduced withoutimpairing the function as the protection element, so that terminalcapacity of the signal terminal can be reduced. That is, diffusionregions 1A and 1B may be separated in the whole part or one part of therange in the Y direction.

Second Exemplary Embodiment

FIGS. 8A and 8B are views showing a layout configuration regarding anESD protection circuit of a semiconductor integrated circuit deviceaccording to a second exemplary embodiment. FIG. 8A is a plan view takenfrom above a substrate, and FIG. 8B is a cross-sectional view takenalong a line A-B in FIG. 8A.

First wiring 11 extends in a Y direction (first direction) in FIG. 8A,and electrically connected to a signal terminal (first terminal) whichis not shown. Second wiring 12 and third wiring 13 extend in the Ydirection similarly to first wiring 11, and arranged on both sides offirst wiring 11, respectively. Second wiring 12 and third wiring 13 areelectrically connected to a power supply terminal or a ground terminalwhich is not shown.

Under first wiring 11, diffusion region 1A serving as a first diffusionregion and diffusion region 1B serving as a second diffusion region areformed. Diffusion region 1A and the diffusion region 1B are separatelyarranged on a side of second wiring 12 and a side of third wiring 13, inan X direction (second direction) in FIG. 8A. In other words, firstwiring 11 extends so as to cover diffusion regions 1A and 1B. Diffusionregions 1A and 1B have the same conductivity type.

Thus, diffusion region 6 is formed so as to surround diffusion regions1A and 1B. Diffusion region 6 has a shape including diffusion region 2formed under second wiring 12 and arranged so as to be opposed todiffusion region 1A in the X direction, and diffusion region 3 formedunder third wiring 13, and arranged so as to be opposed to diffusionregion 1B in the X direction. That is, diffusion regions 2 and 3 areconnected to each other through diffusion regions 7A and 7B formedbeyond both ends of diffusion regions 1A and 1B in the Y direction, andintegrally formed so as to surround diffusion regions 1A and 1B.

First wiring 11, and the diffusion regions 1A and 1B are electricallyconnected through contacts 25. Similarly, second wiring 12 and diffusionregion 2 are electrically connected through contacts 25, and thirdwiring 13 and diffusion region 3 are electrically connected throughcontacts 25.

In this exemplary embodiment also, the same effect as the firstexemplary embodiment can be obtained. That is, diffusion regions 1A and1B provided under first wiring 11 have a configuration in which partsopposed to diffusion regions 2 and 3 are only left and a central part inthe X direction is eliminated. Thus, diffusion capacity can be reducedwithout impairing the function as the protection element. Therefore,terminal capacity of the signal terminal can be reduced. In addition, byensuring a wiring width, the number of contacts, and the number of viaholes to the extent that a surge current can flow, ESD resistance can beprevented from being reduced.

FIGS. 9A and 9B are views showing a variation of this exemplaryembodiment. FIG. 9A is a plan view taken from above a substrate, andFIG. 9B is a cross-sectional view taken along a line A-B in FIG. 9A. InFIG. 9, a component common to that in FIG. 8 is marked with the samereference sign.

A configuration of FIG. 9 is almost the same as that in FIG. 8. However,there is a difference between them in that in a range including thediffusion regions opposed to each other, an interval between wirings islarger than an interval between diffusion regions. Therefore, comparedwith the configuration in FIG. 8, capacity between wirings is alsoreduced, and terminal capacity can be further reduced.

More specifically, in a range including diffusion region 1A anddiffusion region 2 opposed to each other, interval a1 between firstwiring 11 and second wiring 12 is larger than interval b1 betweendiffusion region 1A and diffusion region 2. According to a layout inFIG. 9, diffusion region 1A protrudes toward a side of diffusion region2 from first wiring 11, and diffusion region 2 protrudes toward a sideof diffusion region 1A from second wiring 12, in planar view. Similarly,in a range including diffusion region 1B and diffusion region 3 opposedto each other, interval a2 between first wiring 11 and third wiring 13is larger than interval b2 between diffusion region 1B and diffusionregion 3. According to the layout in FIG. 9, diffusion region 1Bprotrudes toward a side of diffusion region 3 from first wiring 11, anddiffusion region 3 protrudes toward diffusion region 1B from thirdwiring 13, in planar view.

According to this configuration, the interval between first wiring 11and second wiring 12, and the interval between first wiring 11 and thirdwiring 13 are large, so that the capacity between the wirings can bereduced, and terminal capacity can be further reduced.

In addition, similar to the first exemplary embodiment, theconfiguration in this exemplary embodiment may be applied to a casewhere the ESD protection circuit is a diode type, a bipolar transistortype, and a thyristor type. Furthermore, second and third wirings 12 and13 may be electrically connected to a power supply terminal, or may beelectrically connected to a ground terminal. FIGS. 10A and 10B show alayout configuration in which the ESD protection circuit is a thyristortype, in which well 26 is formed around diffusion regions 1A and 1B.

In addition, as shown in FIGS. 11A and 11B, a configuration may be suchthat the number of the parts in which the diffusion regions are dividedis further increased. The configuration in FIG. 11 corresponds to theconfiguration in FIG. 8. Wiring 14 is electrically connected to a signalterminal, and wiring 15 is electrically connected to a power supplyterminal or a ground terminal. Under wiring 14, diffusion regions 4A and4B are formed so as to be arranged separately in the X direction. Inaddition, diffusion region 5 is formed under wiring 15.

In addition, according to the above-described layout configuration,diffusion regions 1A and 1B are separated in a whole part of the rangein the Y direction, but the configuration is not limited to this, and alayout configuration may be such that diffusion regions 1A and 1B arepartially connected and one part of them is separated. In thisconfiguration also, diffusion capacity can be reduced without impairingthe function as the protection element, so that terminal capacity of thesignal terminal can be reduced. That is, diffusion regions 1A and 1B maybe separated in the whole part or one part of the range in the Ydirection.

Third Exemplary Embodiment

A third exemplary embodiment shows a configuration in which a diffusionregion formed under a wiring connected to a signal terminal is notseparated, and an interval between the wirings is larger than aninterval between the diffusion regions.

FIGS. 12A and 12B are views showing a layout configuration regarding anESD protection circuit of a semiconductor integrated circuit deviceaccording to the third exemplary embodiment. FIG. 12A is a plan viewtaken from above a substrate, and FIG. 12B is a cross-sectional viewtaken along a line A-B in FIG. 12A.

First wiring 11 extends in a Y direction (first direction) in FIG. 12A,and electrically connected to a signal terminal which is not shown.Second wiring 12 and third wiring 13 extend in the Y direction similarlyto first wiring 11, and arranged on both sides of first wiring 11,respectively. Second wiring 12 and third wiring 13 are electricallyconnected to a power supply terminal or a ground terminal which is notshown.

Under first wiring 11, diffusion region 31 is formed as a firstdiffusion region. Under second wiring 12, diffusion region 32 is formedas a second diffusion region. Diffusion region 32 is arranged so as tobe opposed to diffusion region 31 in the X direction. In addition, underthird wiring 13, diffusion region 33 is formed as a third diffusionregion. Diffusion region 33 is arranged so as to be opposed to diffusionregion 31 in the X direction. Diffusion regions 32 and 33 have the sameconductivity type.

First wiring 11 and diffusion region 31 are electrically connectedthrough contacts 25. Similarly, second wiring 12 and diffusion region 32are electrically connected through contacts 25, and third wiring 13 anddiffusion region 33 are electrically connected through contacts 25.

Thus, in a range including diffusion region 31 and diffusion region 32opposed to each other, interval a1 between first wiring 11 and secondwiring 12 is larger than interval b1 between diffusion region 31 anddiffusion region 32. According to a layout in FIG. 12, diffusion region31 protrudes toward a side of diffusion region 32 from first wiring 11,and diffusion region 32 protrudes toward a side of diffusion region 31from second wiring 12, in planar view. Similarly, in a range includingdiffusion region 31 and diffusion region 33 opposed to each other,interval a2 between first wiring 11 and third wiring 13 is larger thaninterval b2 between diffusion region 31 and diffusion region 33.According to the layout in FIG. 12, diffusion region 31 protrudes towarda side of diffusion region 33 from first wiring 11, and diffusion region33 protrudes toward a side of diffusion region 31 from third wiring 13,in planar view.

According to this configuration, the interval between first wiring 11and second wiring 12, and the interval between first wiring 11 and thirdwiring 13 are large, so that capacity between the wirings can bereduced, and terminal capacity regarding the signal terminal can bereduced.

FIGS. 13A and 13B are views showing a variation of this exemplaryembodiment. FIG. 13A is a plan view taken from above a substrate, andFIG. 13B is a cross-sectional view taken along a line A-B in FIG. 13A.In FIG. 13, a component common to that in FIG. 12 is marked with thesame reference sign.

A configuration in FIG. 13 is almost the same as that in FIG. 12.However, there is a difference between them in which as for a connectionbetween first wiring 11 and diffusion region 31, contacts 25 for oneline on a side of third wiring 13 are eliminated. As shown in FIG. 13,by eliminating contacts 25 to the extent that discharge of a surgecurrent is not prevented, capacity between contacts 25 can be reduced.

FIGS. 14A and 14B are views showing another example of the layoutconfiguration according to this exemplary embodiment. FIG. 14A is a planview taken from above a substrate, and FIG. 14B is a cross-sectionalview taken along a line A-B in FIG. 14A.

First wiring 11 extends in a Y direction (first direction) in FIG. 14A,and electrically connected to a signal terminal which is not shown.Second wiring 12 and third wiring 13 extend in the Y direction similarlyto first wiring 11, and arranged on both sides of first wiring 11,respectively. Second wiring 12 and third wiring 13 are electricallyconnected to a power supply terminal or a ground terminal which is notshown.

Under first wiring 11, diffusion region 31 is formed. Thus, diffusionregion 36 is formed so as to surround diffusion region 31. Diffusionregion 36 has a shape including diffusion region 32 formed under secondwiring 12 and arranged so as to be opposed to diffusion region 31 in anX direction, and diffusion region 33 formed under third wiring 13, andarranged so as to be opposed to diffusion region 31 in the X direction.That is, diffusion regions 32 and 33 are connected to each other throughdiffusion regions 37A and 37B formed beyond both ends of diffusionregion 31 in the Y direction, and integrally formed so as to surrounddiffusion region 31.

First wiring 11 and diffusion region 31 are electrically connectedthrough contacts 25. Similarly, second wiring 12 and diffusion region 32are electrically connected through contacts 25, and third wiring 13 anddiffusion region 33 are electrically connected through contacts 25.

Thus, in a range including diffusion region 31 and diffusion region 32opposed to each other, interval a1 between first wiring 11 and secondwiring 12 is larger than interval b1 between diffusion region 31 anddiffusion region 32. According to a layout in FIG. 14, diffusion region31 protrudes toward a side of diffusion region 32 from first wiring 11,and diffusion region 32 protrudes toward a side of diffusion region 31from second wiring 12, in planar view. Similarly, in a range includingdiffusion region 31 and diffusion region 33 opposed to each other,interval a2 between first wiring 11 and third wiring 13 is larger thaninterval b2 between diffusion region 31 and diffusion region 33.According to the layout in FIG. 14, diffusion region 31 protrudes towarda side of diffusion region 33 from first wiring 11, and diffusion region33 protrudes toward a side of diffusion region 31 from third wiring 13,in planar view.

According to this configuration, the interval between first wiring 11and second wiring 12, and the interval between first wiring 11 and thirdwiring 13 are large, so that capacity between the wirings can bereduced, and terminal capacity can be reduced.

In addition, similar to the first and second exemplary embodiments, theconfiguration of this exemplary embodiment may be applied to the casewhere the ESD protection circuit is a diode type, a bipolar transistortype, and a thyristor type. Furthermore, second and third wirings 12 and13 may be electrically connected to the power supply terminal, or may beelectrically connected to the ground terminal.

As for the semiconductor integrated circuit device according to thepresent disclosure, the ESD protection circuit can sufficiently fulfillthe ability as the protection element while the terminal capacity of thesignal terminal is kept small, so that it is effective in improving asignal waveform in an LSI in which a high-speed signal is inputted andoutputted, for example.

What is claimed is:
 1. A semiconductor integrated circuit device having an ESD (Electro Static Discharge) protection circuit, wherein: the ESD protection circuit comprises: a first wiring extending in a first direction and electrically connected to a first terminal; a second wiring and a third wiring extending in the first direction, electrically connected to a power supply terminal or a ground terminal, and disposed on both sides of the first wiring respectively; a first diffusion region and a second diffusion region that are connected to and formed under the first wiring, having a same first conductivity type with each other, disposed between the second wiring and the third wiring, in a second direction perpendicular to the first direction, the first and second diffusion regions being at least partially separated from each other; a third diffusion region connected to and formed under the second wiring, having a second conductivity type, and disposed so as to be opposed to the first diffusion region in the second direction; and a fourth diffusion region connected to and formed under the third wiring, having the second conductivity type, and disposed so as to be opposed to the second diffusion region in the second direction, the third diffusion region, the first diffusion region, the second diffusion region and the fourth diffusion region are disposed in this order in the second direction, and the first conductivity type is different from the second conductivity type. 